Assighos to lsster-jokhsoh co



March 20, 1928. 1,663,008 R. W. JOHNSON HEADLIGHT REFLECTOR Filed Feb. 9, 1924 2 Sheets-Sheet 1 [/v VEN TOR fior W J'oH/vsoN i7- ToR/VEYa March 20, 1928.

, 1,663,008 R. W. JOHNSON HEADLIGHT REFLECTOR Filed Feb- 9. 1924 2 Sheets-Sheet Z INYEN To'R' B0) 14 JOHNSON iTraR/YE rs Patented Mar. .20, 1928,

UNITED If; i"

w fiPlaTteier @r ROY WALTER JOHNSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO LESTER-JOHNSON 00., OF

' MINNEAPOLIS. MINNESOTA, A CORPORATION OF MINNESOTA..

' HEADLIGHT nnrrincron.

Application filed February face having as its elements parabolic curves 5 of the same formula and having the same focus, but ha ving'a constantly changing axis in a horizontal plane. I

The object of my invention is to improve the apparatus shown and described in the 10 patent to Lester No. 1, 117 ,926, issued May I do not since this invention may be applied to any limit myselfto the parabola,

other desired conic section curve or modi- 15 fication of such curve.

The invention consists generally in the ap paratus as described and particularly pointed out in the In the accompanying drawings forming part of this specification;

Figures 1 illustrating the method claim.

and 2 are diagrammatic views of generating the reflector surface Figure 3 i s a plan view of the horizontal plane C showing the method of rotation about point Figure 4 shows the pattern of light from a circular parabolic reflector (a) with a theoretical point source of light'at the focus 7 (b) with an electric headlight bulb filament at the focus and 0) from a reflector made as described herein with same bulb filament at focal point;

Figure'5 shows patternfrom new reflector as in 4 ('0) except that the greatest angular spread or movement of ,axis occurs at a point below the horizontal meridan;- I Figure 6 shows the shape of thejmouth, o

a reflector wherein the axis is turned both horizontally HVH' in th and vertically, tracing the path e plane of the reflector-mouth;

Figure? shows pattern of light from reflector as described; (Figure 6) with both vertical tilt axis.

and horizontal spread to the Figure 8 is a. horizontal sectional view on the line 88 of Flgure 9 showing a practical device embodying the nvention. Figure 9 is a View in frontelevation of the reflector.

In Figure 1, planes A, B and C are mutually p erpendicular to each. other,

planes B andC intersecting in the horizontal. line XY, KY and per horizontal.

and A and'B in a line through pendicular to it, plane C being 9.1924, Serial No. centre,

- resulting paraboloid be point F in the axis Now revolve the planes B and C upon point F as a pivot in such a Way that they remain perpendicular to each other and plane C remains perpendicular to plane A. In other words revolve planes B and C in plane C itself using point F as a pivot and retaining Band C perpendicular. to each othe'r,until the line of intersection of B and C makes any desired angle with its original position XY. Let this new position of the intersection of B and C be denoted by MN in Figure 2. Parabola P now as sumes the position P in the plan view of plane C (Figure 3), and the. extremities of its arms are made to lie in plane A by extending or cutting off as required.

The single arm of P which lies outside the original position of said arm in position P is now rotated about its axis, the axis at the same time being turned about F as a center, and remaining in plane C, the two movements to be simultaneous and in such a ratio that when P lies in the vertical plane the axis MN coincides with its original position KY, and that when said arm of P assumes corresponding positions making equal angles on each side of the vertical plane, the angles made by MN and KY are equal. These conditions produce a reflecting surfacewhich is symmetrical about the vertical plane B, and in which the angular movement of the axis MN on either side of its originalposition XY reaches a maximum at any desired pair of elements symmetrical with regard to vertical plane B, said angular movement being zero when the single arm of parabola P lies in the vertical plane; that is after it has rotated 90 and 270.

' This combination of movements produces a reflecting surface composed entirely of parabolic elements having the same formula or focal length and focus point. but with constantly changing angular movement of its 1 their axes about the focus point as a pivot,

all of the axes lying in a horizontal plane.

The effect of such a reflector with the source of light at the focus will be to spread mild light rays :a desired "ratio -starti ng with no spread at the vertical e'len-re'nt and increasing by any desired ratio to certain symmetrical points on each side of "the vertical element, then decreasing .to become zero as the vertical element is reached again 180 from the first position.

' Figure l-shows the pattern of flight from a circular parabolic reflector and the change produced by a reflector .made as described above, the maximum angular movement of the :axes occurring when the single arm P (the .generatrix) lies in the horizontal .plane.

Figure 5 shows the pattern when maximum movement of the axes is reached with P 100 from its upper vertical position instead of 90 as in Figure A.

This invention comprehends the use oit it suitable fixed curve having a focus and the desired characteristics for the projection of light from a single centrally located source oft light within the reflector such, for example, as a standard automobile, headlight bulb. The preferred or specific form of this invention is that .heretofore'described wherein a parabola of suitable toca l length is used to generate the desired surface. It is clear that thecharacteristics of the reflector disclosed above may be variedas to the amount of horizontal-angular movement of the axis, and as to the symmetrical positions of the generating curve P", at which the angular movement of said axis reaches a maximum during the axial rotation of the curve. There are, of course, an infinite number voi? possible pairs of symmetrical points "between the 11 per and lower arms of the vertical meridian, where such maximum angular movement of the axis may arbitrarily be placech These points are determined by actual construction ofdies, using the desired ratio for angular axial movement and rotationangle oi: the generating curve. 1

Reference is now made to Letters Patent of the United States, No. 1,4178%, granted to Charles A. Lester, this invention being designed as an improvement to said patent.

Suppose that in addition to the turning of the axis (MN) about the focus point F as a pivot, in the vertical plane as described in the Lester patent, vnew add a horizontal component of motion in a desired ratio and amount as described in the foregoing specifications, using only a single arm of the parabola P revolved through one complete revolution to produce my desired reflecting surface.

For example .a reflector is desired which itilts or drops'the rays Zilliflllllthfl vertical elements of its surface by 2 degrees (the uppermost rising rays) and decreases this angle to zero at "the horizontal elements. See Figure 6. In addition it is desired to spread the rays horizontally starting with zero at the vertical elements (where the tilt is a maxin um) and. increasing by any desired ratio to a maximum angular horizontal movement of the axis MN of 3 degrees at the horizontal elements. If the movement of the point of the axis "MN lying in ,plane A (the mouthtof the paraboloid) the traced as in Figure '6, :its path will be the.

broken line HVIEU. The contact- ,point of MN with plane A tracing this path twice as follows: 3

lVith the generatrix .P at the upper ver- .t'ical position {(0 \the axis .is at pointy, as

P moves in a clockwise direction -to 9() the axis follows along line H V to 1-1. As P moves to 1-80 the axis retraces lineVH to V,.and as J? .moves to 270 the axis follows line 'HV" to H, retracing back to V during the rotation of P through the fourth quadrant to 0 again.

This motion accords with .theLester pat- .ent .in that the axis moves away from and back toward its original position insuccessive quadrants of the revolution of the parabola. The horizontal component of motion of the axis does not need to, reach a maximum at the horizontal element howeverfbut may occur as in Figure with its maximum above or below the horizontal element as the parabola P is rotated.

I claim as my invention:

A reflector having a continuously-curved reflecting surface non-circular in transverse sectiomflall the elements of said surface being the sameifixed curve of suitable character for the projection of light from a single interior central focus point, but an; acentelements ,havingcontinually changing axes of rotation which pass through said focus point, the intersections of said axes with a plane which is perpendicular to the vertical and horizontal meridian planes of the reflector forming a locus with its ends in the horizontal meridian plane on each side of the vertical meridian plane, and with an termediate point of said locus lying in said vertical meridian plane and below said horizontal meridian plane. i

In witness whereof, I have hereunto set my hand this 31st day of January, 1924. i i f 

